The subject of the present invention is a fire protection blanket, in particular for firestop applications.
By “blanket” is understood a flexible device which is easy to handle, substantially flat in shape, where the thickness is substantially less, even by at least a factor of 5, even for example by at least a factor of 10 than each of the other dimensions.
In general such a blanket is substantially in the form of a parallelepiped. A surface of the blanket or a constituent layer thereof which is perpendicular to the direction of thickness is called the “principal surface”. This principal surface is generally rectangular, but it can also be trapezoidal, have one or more curves, or have any form suitable for protecting a given device against heat propagation, in particular in the case of fire.
Such a blanket is for example used to protect cables and/or ducts in a cable run or means of conveyance of fluid. By “means of conveyance of fluid” is understood any line or carrier of a fluid in the wide sense, gas or liquid.
The cables or ducts generally contain wires or fibres such as for example electrical power or signalling wires, coaxial cables or optical fibres.
It is in fact very important, even essential, to be able to protect cables or ducts or means of conveyance of fluid during a fire, for example at least to protect the cables containing wires connected to sensors, particularly fire sensors, or to control means, particularly with a view to extinguishing a fire or triggering an alarm or safety device.
A particular case of a device where rigorous fire protection must be provided relates to inspection chambers. Such chambers are cavities making it possible to gain access to embedded cable runs. They are for example distributed at regular intervals over long  distances to allow initially for the cables to be pulled through and subsequently for their inspection.
Generally, inspection chambers are in the form of a parallelepiped, comprising a removable face and two faces suitable for openings to be made capable of allowing cables, ducts or means of conveyance of fluid to pass through. Such inspection chambers are in particular installed embedded in tunnels, and are substantially flush with the level of the carriageway. Safety requirements in the tunnels are particularly high and there is a need to find improved means of fire protection, particularly for this type of application.